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v3.25.3

DEBT - ABL Credit Facility - Narrative (Details) - USD ($) | Sep. 29, 2025 | Mar. 24, 2023 | May 26, 2021 | Sep. 30, 2025 | Sep. 30, 2024
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Senior Term Loan Facility Due September 29, 2032 | Secured Debt |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Debt instrument, extended term, period prior to maturity date | 91 days |  |  |  |
Line of credit facility, term, outstanding obligations threshold amount | $ 100,000,000 |  |  |  |
Senior Term Loan Facility Due September 29, 2032 | Alternate Base Rate | Secured Debt |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Debt instrument, basis spread on variable rate | 1.00% |  |  |  |
Domestic Line of Credit | Amended ABL Credit Facility | LIBOR | Minimum |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Debt instrument, basis spread on variable rate |  |  | 1.25% |  |
Domestic Line of Credit | Amended ABL Credit Facility | LIBOR | Maximum |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Debt instrument, basis spread on variable rate |  |  | 1.75% |  |
Domestic Line of Credit | Amended ABL Credit Facility | Alternate Base Rate | Minimum |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Debt instrument, basis spread on variable rate |  |  | 0.25% |  |
Domestic Line of Credit | Amended ABL Credit Facility | Alternate Base Rate | Maximum |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Debt instrument, basis spread on variable rate |  |  | 0.75% |  |
Domestic Line of Credit | Amended ABL Credit Facility | Secured Overnight Financing Rate SOFR |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Credit spread adjustment |  | 0.10% |  |  |
Domestic Line of Credit | Amended ABL Credit Facility | Secured Overnight Financing Rate SOFR | Minimum |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Debt instrument, basis spread on variable rate |  | 1.25% |  |  |
Domestic Line of Credit | Amended ABL Credit Facility | Secured Overnight Financing Rate SOFR | Maximum |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Debt instrument, basis spread on variable rate |  | 1.75% |  |  |
Foreign Line of Credit | Amended ABL Credit Facility | Line Of Credit Facility, Commitment Option One |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Line of credit facility, unused capacity, commitment fee percentage |  |  | 0.375% |  |
Foreign Line of Credit | Amended ABL Credit Facility | Line Of Credit Facility, Commitment Option Two |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Line of credit facility, unused capacity, commitment fee percentage |  |  | 0.30% |  |
Foreign Line of Credit | Amended ABL Credit Facility | Line Of Credit Facility, Commitment Option Three |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Line of credit facility, unused capacity, commitment fee percentage |  |  | 0.25% |  |
Foreign Line of Credit | Amended ABL Credit Facility | Bankers Acceptance Rate | Minimum |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Debt instrument, basis spread on variable rate |  |  | 1.25% |  |
Foreign Line of Credit | Amended ABL Credit Facility | Bankers Acceptance Rate | Maximum |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Debt instrument, basis spread on variable rate |  |  | 1.75% |  |
Foreign Line of Credit | Amended ABL Credit Facility | Prime Rate | Minimum |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Debt instrument, basis spread on variable rate |  |  | 0.25% |  |
Foreign Line of Credit | Amended ABL Credit Facility | Prime Rate | Maximum |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Debt instrument, basis spread on variable rate |  |  | 0.75% |  |
Line of Credit | Amended ABL Credit Facility | Secured Debt |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Debt instrument, extended term, period from amendment date |  |  | 5 years |  |
Debt instrument, extended term, period prior to maturity date |  |  | 91 days |  |
Line of credit facility, term, outstanding obligations threshold amount |  |  | $ 100,000,000 |  |
Atkore International | Line of Credit | Amended ABL Credit Facility |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Aggregate commitments |  |  |  | $ 325,000,000 |
Credit availability |  |  |  | $ 325,000,000 | $ 325,000,000
Borrowing base percentage of eligible accounts receivable (%) |  |  |  | 85.00% |
Borrowing base percentage of eligible inventory (plus) (%) |  |  |  | 80.00% |
Debt instrument, covenant, borrowing base, percentage of inventory subject to certain limitations (%) |  |  |  | 85.00% |
Borrowings outstanding |  |  |  | $ 0 | $ 0

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